Switch EXPLAIN to unaligned output for json/xml/yaml

Switch EXPLAIN to unaligned output for json/xml/yaml

Use unaligned output for multiple EXPLAIN queries using non-text format
in regression tests. With aligned output adding/removing explain fields
can be very disruptive, as it often modifies the whole block because of
padding. Unaligned output does not have this issue.

Author: Tomas Vondra <tomas@vondra.me>
Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/flat/a177a6dd-240b-455a-8f25-aca0b1c08c6e%40vondra.me